Here's the card itself: Much like the other cards in Rise of the Floodborn, this version of Arthur veers away from the original version for something more adventurous
Combine this with cards like God-Pharaoh's Statue and other similar taxing effects and your opponents will have to pay upward of six mana just to cast one spell
P/T Number 5 Language English Legal Formats Commander, Historic, Legacy, Modern, Vintage Not Legal Formats Alchemy, Brawl, Competitive Brawl, Pauper, Pioneer, Standard, Timeless Rulings (12/8/2022) The token created by Urza's first ability will count itself, so it'll be at least 1/1
Kastrals inclusion is a bit sketchier since five-mana is a lot for a creature deck in the current Standard, but if this deck can weather the opening turns, Kastral gives the Bird Typal deck a ton of agency